Hydrogen Isotope Research Articles

A Mini Review on Liquid Phase Catalytic Exchange for Hydrogen Isotope Separation: Current Status and Future Potential

Liquid phase catalytic exchange (LPCE) appears a highly promising technology for separating hydrogen isotopes due to being less energy-intensive and having a high separation factor. This paper provides an overview of the current development of the hydrophobic catalysts used in the LPCE process, including the LPCE fundamentals, factors influencing its effectiveness, and proposals for future research areas. This paper specifically reviews the active metal catalysts, catalyst supports, operating temperatures, and molar feed ratio(gas-to-liquid,G/L). The addition of a second metal such as Ir, Fe, Ru, Ni, or Cr and modified catalyst supports showed enhancement of LPCE performance. Additionally, the validated optimized temperature of 60–80 °C and G/L of 1.5–2.5 provide an important basis for designing LPCE systems to improve separation efficiency. This paper concludes by highlighting potential research areas and challenges for future advancements in the sustainability of LPCE for hydrogen isotope separation, which include the optimization, scalability, techno-economic analysis, and life-cycle analysis of modified catalyst materials.

Hydrogen isotope population near dislocations in zirconium from molecular dynamics

Performance of zirconium tritides used for hydrogen isotope storage is significantly changed under reactor environments. This can be attributed to the formation of various radiation-induced dislocations. To help gain insight, molecular dynamics simulations have been employed to investigate hydrogen isotope population in zirconium containing different types of edge dislocations. Our studies reveal that hydrogen isotope concentration is highest near the tensile side of dislocation cores and varies based on dislocation type. This increase in hydrogen isotope concentration can be explained by the Boltzmann equation based on calculations using swelling volume and pressure field, with significantly reduced computational cost. Strikingly, because hydrogen isotope in the compressive regions of dislocations is depleted, the overall hydrogen isotope content is found to be unchanged by dislocation formation. These results counter the previous view that the dislocation trapping effect increases hydrogen isotope solubility and provide an understanding of changes in hydrogen isotope pressure under reactor conditions. By elucidating the impact of dislocations on hydrogen isotope storage performance, this research offers insights for optimizing zirconium tritides in nuclear applications. and contributes to the advancement of hydrogen isotope storage materials.

Hydrogen isotope effect on thermodynamic and kinetic properties of Pd based ternary alloys: Pd–Ag-M (M = Au, Zr)

Owing to the importance of hydrogen and its isotopes in energy sector, the present study investigates thermodynamic and kinetic hydrogen isotope effects on desorption reaction of newly synthesized Pd-based ternary alloy-hydrides/deuterides viz., Pd0.89Ag0.05M0.06 (M = Au, Zr)–H/D. Alloys were prepared by arc melting method followed by characterization using PXRD, SEM, TXRF and EDX techniques. The effect of hydrogen isotopes on thermodynamics of H2/D2 desorption reaction was investigated by generating pressure-temperature isotherms (PCIs) at various temperatures using a Sieverts' type volumetric apparatus. The PCT diagram of alloys depicts a single plateau which confirms desorption to be a one-step process. Both alloy systems display a normal isotope effect as indicated by higher plateau pressure for deuterides as compared to hydrides. The enthalpy and entropy changes for the desorption reactions were calculated using Van't Hoff equation. The separation factor derived from PCT data indicates that Pd0.89Ag0.05Au0.06 alloy has a significantly high separation factor as compared to other Pd based alloys reported in the literature. To get more insight into this behavior, non-isothermal kinetic analysis of H2/D2 desorption based on Differential Scanning Calorimeter (DSC) data acquired at four different heating rates was conducted and activation energies of desorption were calculated by invoking Kissinger's equation. The activation energies of alloys were found to be lower than that of palladium which explains the high separation factor of alloys as compared to Pd. The desired combination of higher separation factor and lower activation energy makes Pd0.89Ag0.05Au0.06 alloy a promising material for practical application in the separation of hydrogen isotopes via self-displacement gas chromatography (SDGC).

Deuterium permeation performance of V4Cr4Ti/RAFM steel joint with in-situ formed carbide interlayer during diffusion bonding

Vanadium alloy (V4Cr4Ti) is a structural material used in future fusion reactors owing to its inherent advantages of high-temperature strength and neutron irradiation resistance. Oxygen pickup and high hydrogen isotope permeability are the two major concerns for their application in various types of blankets. To solve these issues, a bimetallic joint was designed with a CLF-1 layer of reduced-activation ferritic/martensitic (RAFM) steel to resist corrosion and a CLF-1/V4Cr4Ti bonding interface to suppress hydrogen isotope permeation. Samples were prepared from joints bonded via solid-state diffusion under hot isostatic pressing (HIP). Deuterium (D) gas permeation tests were performed at various temperatures in the range 400–600 °C at 100 kPa. After deuterium permeation tests, the thermal desorption spectra (TDS) of the samples were analyzed. And the permeation behavior of deuterium atom across the joints was schematically discussed. The results showed that bonding with steel could be an effective solution for resisting hydrogen isotope permeation through the V4Cr4Ti alloy. Thermal desorption spectrum (TDS) analysis of the tested samples revealed a desorption peak temperature equivalent to that of TiC. The formation of a 1 µm-wide B2 ordered α'- [Fe, (V, Ti)] phase layer, together with a large number of dispersed carbides around the interface, played a significant role in the deuterium permeation resistance. In addition, microstructural changes in the steel base material after the 900 °C bonding process were beneficial for suppressing deuterium diffusion.

Laser Diagnostics of Content of Hydrogen Isotopes in the Globus-M2 Tokamak Wall

Laser Diagnostics of Content of Hydrogen Isotopes in the Globus-M2 Tokamak Wall

NiP2 as an efficient non-noble metal cathode catalyst for enhanced hydrogen isotope separation in proton exchange membrane water electrolysis

Proton exchange membrane (PEM) water electrolysis is crucial for efficient hydrogen isotope separation (HIS) in liquid water. However, current cathode catalysts like platinum (Pt) suffer from scarcity and limited HIS performance. To overcome this challenge, we propose a simple and effective approach involving the synthesis of highly dispersed NiP2 nanoparticles supported on carbon (NiP2/C) through a solid-phase phosphidation reaction, and for the first time report its enhanced HIS performance as the cathode catalyst in PEM electrolyzer. The NiP2/C catalyst demonstrates excellent catalytic properties as a cathode catalyst for hydrogen evolution reaction (HER) in an acidic electrolyte, achieving low overpotential of only 157 mV at 10 mA/cm2 and Tafel slope of 95.6 mV/dec. Meticulous investigations and density functional theory (DFT) calculations reveal the intrinsic factors behind its performance. Furthermore, DFT calculations predict the HIS performance of both NiP2/C and Ni/C catalysts, revealing the advantages of NiP2/C over Ni/C. Experimental results obtained in practical PEM water electrolysis validate these predictions, as NiP2/C exhibits an impressive separation factor α of 6.36, nearly twice that of the Pt/C catalyst. Moreover, NiP2/C demonstrates reliable and consistent HIS performance during a 100-hour PEM electrolysis process. Importantly, our calculation model for deuterium enrichment in liquid water reveals that catalysts with higher separation factors α show faster deuterium enrichment and higher deuterium recovery rates. The utilization of NiP2/C as a non-noble metal cathode catalyst holds great promise for efficient and sustainable hydrogen isotope separation, addressing the limitations of precious metal catalysts and advancing clean energy technologies.

Compound-specific stable isotope analyses of fatty acids indicate feeding zones of zooplankton across the water column of a subalpine lake

Spatial and temporal zooplankton feeding dynamics across the water column of lakes are key for understanding site-specific acquisition of diet sources. During this 6-week lake study, we examined stable carbon (δ13C) and nitrogen (δ15N) isotopes and conducted compound-specific fatty acid (FA) stable isotope analysis (CSIA) of edible seston in the epi-, meta-, and hypolimnion, and zooplankton of Lake Lunz, Austria. We predicted that CSIA of essential FA can discern the foraging grounds of zooplankton more accurately than the commonly used bulk stable isotopes. The δ13C and δ15N values of seston from different lake strata were similar, whereas a dual CSIA approach using stable carbon and hydrogen isotopes of FA (δ13CFA and δ2HFA) provided sufficient isotopic difference in essential FA to discern different lake strata-specific diet sources throughout the study period. We present a CSIA model that suggests strata-specific foraging grounds for different zooplankton groups, indicating higher preference of cladocerans for feeding on epilimnetic diet sources, while calanoid copepods retained more hypolimnetic resources. The CSIA approach thus yields strata-specific information on foraging strategies of different zooplankton taxa and provides more details on the spatial and temporal trophodynamics of planktonic food webs than commonly used bulk stable isotopes.

Selectively enriching accessible quantum sieving sites in two‐dimensional carbons for D2/H2 kinetic separation

AbstractSeparation of hydrogen isotopes (D2/H2) attracts wide interest due to its important applications, such as nuclear fusion. Kinetic quantum sieving‐induced separation over tailored nanoporous solids is a promising method; however, the dynamic separation often shows a transient feature, thus a low D2/H2 selectivity even at temperature below 50 K. Herein, we selectively enriched the accessible quantum sieving (AQS) sites in two‐dimensional carbons by chemically growing a pore‐narrowing layer. The spatial density of such AQS sites is 8.5 times higher than that of commercial carbon molecular sieves. The kinetic selectivity of D2/H2 reached 4.6 at 77 K. Column breakthrough experiments revealed that the dynamic D2/H2 separation was enhanced by such a nanopore design. Aspen simulation indicated that D2 was enriched to 93.1% within 11 pressure swing adsorption cycles with a 1% D2/99% H2 mixture as feed.

Integrating machine learning with -SAS for enhanced structural analysis in small-angle scattering: applications in biological and artificial macromolecular complexes.

Small-Angle Scattering (SAS), encompassing both X-ray (SAXS) and Neutron (SANS) techniques, is a crucial tool for structural analysis at the nanoscale, particularly in the realm of biological macromolecules. This paper explores the intricacies of SAS, emphasizing its application in studying complex biological systems and the challenges associated with sample preparation and data analysis. We highlight the use of neutron-scattering properties of hydrogen isotopes and isotopic labeling in SANS for probing structures within multi-subunit complexes, employing techniques like contrast variation (CV) for detailed structural analysis. However, traditional SAS analysis methods, such as Guinier and Kratky plots, are limited by their partial use of available data and inability to operate without substantial a priori knowledge of the sample's chemical composition. To overcome these limitations, we introduce a novel approach integrating -SAS, a computational method for simulating SANS with CV, with machine learning (ML). This approach enables the accurate prediction of scattering contrast in multicomponent macromolecular complexes, reducing the need for extensive sample preparation and computational resources. -SAS, utilizing Monte Carlo methods, generates comprehensive datasets from which structural invariants can be extracted, enhancing our understanding of the macromolecular form factor in dilute systems. The paper demonstrates the effectiveness of this integrated approach through its application to two case studies: Janus particles, an artificial structure with a known SAS intensity and contrast, and a biological system involving RNA polymerase II in complex with Rtt103. These examples illustrate the method's capability to provide detailed structural insights, showcasing its potential as a powerful tool for advanced SAS analysis in structural biology.

Enhanced Solar-to-Hydrogen Conversion and Hydrogen Isotope Separation through Interfacial Hydrogen-Bond Engineering and Homolytic O–H Cleavage on Multianionic Sulfides in Large-Scale Floating Nanocomposites

Enhanced Solar-to-Hydrogen Conversion and Hydrogen Isotope Separation through Interfacial Hydrogen-Bond Engineering and Homolytic O–H Cleavage on Multianionic Sulfides in Large-Scale Floating Nanocomposites

Competitive barrier and trapping effects of helium bubbles on hydrogen isotopes migration behavior in tungsten

In fusion reactors, plasma-facing materials will be exposed to low-energy and high-flux plasma of the hydrogen isotopes fuel, i.e., deuterium (D) and tritium (T), along with helium (He), the product of nuclear fusion reactions. He irradiation is likely to trigger the formation of He bubbles beneath the material surface, exerting complex effects on the migration patterns of hydrogen isotopes. In this work, molecular dynamics simulations were employed to investigate the influence of nano-sized He bubbles on the D migration behavior in tungsten (W) during the continuous implantation and diffusion processes, which is more consistent with the fusion environment for plasma-facing materials. It is found that the influence of He bubbles on D migration behavior can be classified into barrier and trapping effects. These effects show a competitive relationship at different processes. During the implantation process, the barrier effect takes precedence over the trapping effect, leading to the reduced D retention. Conversely, during the diffusion process, the trapping effect dominates over the barrier effect, resulting in increased D retention. Due to the surface of He bubbles serves as the trapping sites for hydrogen isotopes, augmenting the size and density of He bubbles notably enriches the strong trapping sites in W. When the location of He bubble is closer to the surface, a higher frequency of interaction events occurs between the implanted D atoms and He bubbles, consequently increasing D retention. Additionally, it was also found that the lattice distortion in pure W is more pronounced than that in He bubble-containing W at high temperatures due to the robust interaction between D and He, which diminishes collisions between D atoms and the W lattice. This study gives a valuable insight into the influence of He bubbles on hydrogen isotopes migration behavior in the fusion environment.

A tipping point in stable isotope composition of Antarctic meteoric waters during Cenozoic glaciation

Triple oxygen isotopes of Cenozoic intrusive rocks emplaced along the Ross Sea coastline in Antarctica, reveal that meteoric-hydrothermal waters imprinted their stable isotope composition on mineral phases, leaving a clear record of oxygen and hydrogen isotope variations during the establishment of the polar cap. Calculated O- and H-isotope compositions of meteoric waters vary from −9 ± 2‰ and −92 ± 5‰ at 40 ± 0.6 Ma, to −30 and −234 ± 5‰ at 34 ± 1.9 Ma, and intersect the modern Global Meteoric Water Line. These isotopic variations likely depict the combined variations in temperature, humidity, and moisture source regions, resulting from rearrangement of oceanic currents and atmospheric cooling during the onset of continental ice cap. Here, we report a paleo-climatic proxy based on triple oxygen geochemistry of crystalline rocks that reveals changes in the hydrological cycle. We discuss the magnitude of temperature changes at high latitudes during the Eocene-Oligocene climatic transition.

Enhancing analytical merits of laser-induced breakdown spectroscopy of hydrogen isotopes using an orthogonal double-pulsing scheme

Accurate detection and quantification of hydrogen isotopes in solid materials are vital for diverse applications, including fusion energy, hydrogen storage, and tritium production. Laser-induced breakdown spectroscopy (LIBS) is a well-established, rapid, standoff method for this purpose, but it faces challenges related to the analytical merits required for isotopic analyses. In this study, we enhance the analytical and detection capabilities of traditional single-pulse LIBS by implementing an orthogonal double pulsing approach, focusing on the analysis of a range of 2H concentrations in Zircaloy-4 substrates (acting as a proxy for 3H). The double-pulse experiments employed an orthogonal re-heating configuration with two nanosecond Nd:YAG lasers. We systematically evaluated critical parameters affecting the signal intensity in double-pulse LIBS, including interpulse delay, ambient gas pressure, and heating laser energy. Our results demonstrate that employing an orthogonal double-pulse scheme significantly enhances 2Hα emission while minimizing line broadening and self-absorption, ultimately improving the technique's analytical capabilities.

Solubility of Hydrogen in a WMoTaNbV High-Entropy Alloy.

The WMoTaNbV alloy has shown promise for applications as a solid state hydrogen storage material. It absorbs significant quantities of H directly from the atmosphere, trapping it with high energy. In this work, the dynamics of the absorption of hydrogen isotopes are studied by determining the activation energy for the solubility and the solution enthalpy of H in the WMoTaNbV alloy. The activation energy was studied by heating samples in a H atmosphere at temperatures ranging from 20 °C to 400 °C and comparing the amounts of absorbed H. The solution activation energy EA of H was determined to be EA=0.22±0.02 eV (21.2 ± 1.9 kJ/mol). The performed density functional theory calculations revealed that the neighbouring host atoms strongly influenced the solution enthalpy, leading to a range of theoretical values from -0.40 eV to 0.29 eV (-38.6 kJ/mol to 28.0 kJ/mol).

Lower crustal control in the iron isotope systematics of plutonic xenoliths from Adak Island, Central Aleutians, with implications for arc magma geochemistry

We present bulk-rock and mineral Fe isotope data of ultramafic to mafic xenoliths and basaltic to andesitic lavas from Adagdak Volcano (Adak Island, Central Aleutians) to study the effects of early differentiation on the Fe isotopic evolution of island arc basalts and their crystallization products. The Fe isotope composition of ultramafic cumulate xenoliths increases from dunite (δ56Fe = –0.09 to –0.02 ‰) to clinopyroxenite (δ56Fe = +0.06 to +0.09 ‰), consistent with higher modal proportions of clinopyroxene (δ56Fe = –0.05 to +0.11 ‰) relative to olivine (δ56Fe = –0.10 to +0.06 ‰) in the latter. Mid-crustal cumulate amphibole gabbro and hornblendite cumulates also record heavier Fe isotope compositions (δ56Fe = +0.04 to +0.08 ‰) due to the abundance of isotopically heavy amphibole (δ56Fe = +0.07 to +0.09 ‰) and magnetite (δ56Fe = +0.11 to +0.13 ‰) in these rocks. High inter-mineral fractionations observed in spinel-olivine and spinel-clinopyroxene pairs (Δ56Fespl-ol = +0.12 to +0.28 and Δ56Fespl-cpx = +0.06 to +0.19) suggest that spinel is not recording equilibrium crystallization conditions for the ultramafic assemblages, likely due to subsolidus Fe-Mg exchange. Our data also include Fe isotope measurements of one mantle dunite (δ56Fe = +0.03 ± 0.05 ‰). Five Adagdak lavas, spanning from basalts to andesites, yield a narrow range of δ56Fe between +0.03 and +0.06 ‰. Our results highlight the potential of amphibole in driving the Fe isotope depletion trends observed in many erupted arc lavas, as amphibole hosts 28–99 % of the FeOT budget in the amphibole gabbro and hornblendite cumulates. This is also supported by single-crystal synchrotron Mössbauer spectroscopy of two amphibole grains, the first from an amphibole gabbro and the second from a hornblendite, which yield Fe3+/ΣFe ratios of 0.55 ± 0.06 and 0.58 ± 0.02, respectively. Water content and hydrogen isotope compositions determined by secondary-ion mass spectrometry from the same amphibole grains indicate partial dehydrogenation. Using Rayleigh fractionation modeling to account for oxidation during post-crystallization dehydrogenation, we calculate magmatic Fe3+/ΣFe ratios of 0.41 ± 0.04 for the amphibole gabbro and 0.30 ± 0.05 for the hornblendite. These data are then used to estimate an appropriate Fe force constant for Adagdak amphibole and quantitatively evaluate the effects of amphibole fractionation. Through a fractional crystallization model, we show how arc melts may experience periods of increasing δ56Fe during olivine-dominated fractionation, followed by decreasing δ56Fe once magnetite and amphibole saturate as cumulate phases. Notably, this dichotomy between fractionation of isotopically light versus heavy cumulate assemblages and its effects on the Fe isotope evolution of arc magmas is not captured by the Adagdak lava record, highlighting the utility of cumulates in chronicling the early isotopic evolution of magmatic systems.

Stable Isotope Hydrology of Karst Groundwaters in Romania

In this article we present the first investigation of the stable isotope composition of groundwater in Romania, East-Central Europe, with a focus on the karst areas. Our aim is twofold: (1) to provide a countrywide map with the distribution of stable oxygen and hydrogen isotope ratios in groundwater, and (2) to assess the recharge patterns of karst water. We collected more than 600 water samples from springs and wells across Romania for stable isotope analyses and monitored in detail the stable isotope composition of the waters as they pass through five cave systems. Our data show a spatial distribution of the stable isotope composition of the groundwater with low values in the mountainous area and high values in the surrounding lowlands and the central Transylvanian Depression. However, waters in karst areas induce departures from this distribution, resulting from the fast (hours to days) transfer of waters from high (ponor) to low (spring) altitudes. Water emerging from the karst springs has generally lower δ values than before sinking through the ponors, thus indicating a substantial contribution of winter recharge through diffuse infiltration and seepage. This contribution results in overall dilution of the water entering through ponors, likely resulting in changes in the chemical composition of the water and diluting potential pollutants. Our data call for careful separation between karst and non-karst spring/well waters, as indiscriminate common treatment might lead to erroneous interpretations.

Effects of the diffusion path on the effective diffusion coefficient of hydrogen isotope in tungsten with helium bubbles

In irradiated tungsten (W), the formation of numerous helium (He) bubbles has a significant impact on the diffusion behaviors of hydrogen (H) isotopes. To investigate the influence of the microstructure of He bubbles on the diffusion behaviors of deuterium (D), we utilize the reconstructed experimental data, the phase-field method, and the steady-state diffusion equation to calculate the effective diffusion coefficients of D based on four possible diffusion paths, i.e., D atoms diffuse in the bulk W, inside the He bubbles, and along the outer and inner surface of He bubbles. Simulation results based on the reconstructed depth-dependent distribution of He bubbles reveal that the diffusion paths remarkably affect the effective diffusion coefficient of D. By varying the radius and number density of He bubbles, the effective diffusion coefficient of D undergoes significant changes. Subsequently, we fit an empirical formula of the effective diffusion coefficient of D as a function of the radius and number density of He bubbles for different diffusion paths of D based on simulation data. Besides, the growth behaviors of He bubbles are simulated by the phase-field model, and the effective diffusion coefficient of D as a function of the evolutionary time for different diffusion paths is also discussed. At last, we investigate the influence of the D concentration and temperature on the effective diffusion coefficient of D along different diffusion paths. These results indicate that the effective diffusion coefficient of D increases with decreasing the D concentration and increasing the temperature for four diffusion paths. The current study provides a reference for investigating the diffusion behaviors of D in W in the presence of He bubbles, and may benefit the efforts of developing low D retention W-based materials.

Evolution of hydrogen isotopes retention behavior of in-situ boronization films in EAST

Effective management of hydrogen isotopes retention in plasma-facing materials (PFMs) is crucial, particularly when utilizing tritium (T) as fuel, for the success of burning plasma operations. Boronization, a widely employed technique for controlling fuel recycling and mitigating impurity influx from plasma-surface interactions into the core of burning plasma, significantly influences hydrogen isotopes retention in PFMs. In this study, boronization films were generated by ion cyclotron range of frequency (ICRF) discharge assisted boronization with C2B10H12 as boron source on tungsten substrates at Experimental Advanced Superconducting Tokamak (EAST) which employing ITER-like water-cooled W monoblock PFMs and components (PFCs), followed by in-situ glow discharge (GD) cleaning for 2 h and 20 shots (180 s) edge-plasma exposure. Employing the Material and Plasma Evaluation System (MAPES), representative samples were analyzed after each process. The resultant carbon–boron films, dense and continuous, exhibited thickness up to 120 nm and were identified as amorphous in structure. It was observed that the D2-GD cleaning resulted in a significant isotopic exchange effect, effectively reducing the hydrogen (H) retention in the carbon–boron films. This hydrogen isotope replacement efficiency was found to be influenced by the thickness of the films. Notably, after boundary plasma exposure, samples with thicker films demonstrated an enhanced capacity to capture deuterium (D), adsorbing 10 times more D than bare tungsten (W). Our findings offer transformative insights for T recycling analysis and the plasma operation of devices like International Thermonuclear Experimental Reactor (ITER), highlighting the impact of boronization and subsequent treatments on hydrogen isotope retention behavior in PFMs.

Origin of bluish pectolite aka larimar from the Dominican Republic: Constraints from mineralogy and geochemistry

The commonly known larimar is usually a gem-quality, bluish pectolite (NaCa2Si3O8OH), intergrown with other associated minerals such as natrolite, prehnite, calcite, chlorite, found only in the Dominican Republic. Less frequently it shows consecutive and/or sequential green, blue, and white coloration within single amygdales/veins developed in altered (chloritized, serpentinized) Cretaceous basalts of the Dumisseau Formation. The origin of larimar is linked to the circulation of low-temperature (<170 °C) alkali-rich deuteric fluids that were later mixed with meteoric waters. Variations of CL colors, ranging from weak brown in green pectolite to strong yellow (Mn2+-activated) in blue and white species, were ascribed to the transition from oxic to suboxic crystallization environment within the single larimar bodies. These changes could be induced by the burial of magmatic rocks and resulted in the emergence of early zeolite (natrolite), and subsequent formation of native copper in a sulphur-deficient hydrothermal environment. Pectolite-forming elements (e.g. Ca and Na), followed by such transition metals as Cu, Cr, Co, and Ni, were released via the alterations of magmatic minerals (diopside, aegirine-augite, and chromite-magnetite) and/or leached from basaltic groundmass. Decoupling between δ18O values of blue (up to 10.67‰), green (up to 9.66‰), and white pectolite (up to 15‰) was maintained by a progressive temperature drop during ongoing pectolitization and/or presence of the boiling-related environment. Meanwhile, anomalously low δD values (from −390.51‰ to −294.02‰) indicate that the crystal structure of pectolite tends to incorporate light hydrogen isotope regardless of the original δD values in mineralizing fluids.

Laser-induced breakdown spectroscopy for helium detection in beryllium coatings

Laser Induced Breakdown Spectroscopy (LIBS) method is considered to be a promising tool for analyzing the retention of hydrogen isotopes (D and T) and helium (He) on the first walls and divertor regions of future fusion reactors. Helium will be produced in DT reactions but could also be used in the initial non-nuclear phases of DEMO concepts. The present study investigates the He detection by LIBS method in the Be coatings simulating the deposits on the divertor plasma-facing components of JET while the results are also relevant for He detection in the deposits of other wall materials. The study was carried out in a vacuum vessel filled with 2–40 mbar argon background gas. It was shown that 2.8 at. % of He was confidently detectable by LIBS at optimized measurement conditions and the estimated limit of detection at used experimental conditions is approximately 0.7 at. %. The intensity of the He emission line at 587.56 nm was the strongest at the center of the laser-induced plasma plume. The He line intensity increased with the pressure of Ar gas but the broadening of the He line and the increase of the background emission and noise set an upper limit to the Ar background pressure usable for He detection. The application of the calibration-free LIBS procedure resulted in the overestimation of the He/Be ratio by several orders of magnitude. The overestimation can be explained by the deviation of LIBS plasma from the local thermodynamic equilibrium, which is caused by the very high excitation energy of He atoms.